"Stories We Tell" is a documentary about Sarah Polley's family: her father and mother, sister and brother and the sister and brother she has from her mother's first marriage. It's about moments they've shared that are seemingly prosaic and universally relatable, depicted through the grainy, faded nostalgia of Super 8 - splashing in the swimming pool, laughing around the dinner table - as well as the betrayals and losses that shaped and strengthened them.

But while it's incredibly specific in its detail and makes you feel as if you've known these people forever after spending less than two hours with them, "Stories We Tell" is also about every family. It reveals that we'll all unreliable narrators of our own histories, especially after years and even decades have gone by. And it reminds us that the truth is a fleeting thing, constantly changing in the slightest of ways depending on who's telling it.

Polley, the Toronto-based actress-turned-filmmaker, has shown astonishing emotional depth and technical maturity at a young age in just two previous features: "Away From Her" and "Take This Waltz." Like those earlier films, "Stories We Tell" focuses on how a long-term relationship evolves over time. Now 34 and tackling a subject that's so close to her heart, she reveals a whole new level of artistic mastery. Her meta, multilayered exploration of her own past combines interviews, archival footage and meticulous reenactments so seamlessly, it's hard to tell what's real and what's mythologized. And that's the point.

Even calling "Stories We Tell" a documentary seems rather limiting and not entirely accurate; it's also a deadpan comedy, a juicy melodrama and a gripping mystery, all cleverly blended together with great focus. But Polley pulls back the curtain from time to time to share her process, which creates an even greater sense of intimacy. Her siblings squirm beneath a boom mic and hot lights, worrying about how they look. Her father, the actor Michael Polley, stands at a microphone in a recording studio, reading in a rich, British accent his own poetic version of the family's history that he wrote; Polley, sitting at a sound board on the other side of the glass, politely instructs him to repeat a line here and there.

Their bond is obviously a warm and comfortable one, and has remained so despite the revelations that the film recounts. (Do NOT do a Google search before you see this movie. Experience it for yourself.)

"Stories We Tell" sprang from a recurring joke within the Polley family that Sarah didn't resemble her father much. Relatives and longtime friends remember her mother, Diane Polley, who died of cancer when Sarah was only 11, as a charismatic, fun-loving stage actress. But she also had secrets. Polley sat all these people down in front of a camera, one by one, and asked them to tell her the family's story as if she were meeting them for the first time. (The fact that these anecdotes are sprinkled with healthy helpings of dry, self-effacing Canadian humor makes us want to get to know these people even more.)

Because we are seeing the same moments over and over, as recalled from varying perspectives, "Stories We Tell" grows a tad repetitive, and the proliferation of shaky, hand-held camera can be a little dizzying.

Even more powerful, though, is the overwhelming sense of discovery, the relief of catharsis, and the rush of uplift at the conclusion.

"Stories We Tell," a Roadside Attractions release, is rated PG-13 for thematic elements involving sexuality, brief strong language and smoking. Running time: 108 minutes. Three and a half stars out of four.

---

Motion Picture Association of America rating definition for PG-13: Parents strongly cautioned. Some material may be inappropriate for children under 13.